https://ethereum.stackexchange.com/questions/21448/how-to-get-a-contracts-balance-in-solidity

 function contractbalance() public view returns (uint256){  
        return address(this).balance;  
    }


var thecontract = web3.eth.contract([{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"gett","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"buy","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Set","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"tokens","type":"uint256"}],"name":"Buyvalue","type":"event"}]);  
var MyContract = thecontract.at('0xbed0229199614a11e47c39d4800420de968627fa');  
  
MyContract.buy({  
  from:'0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176',   
  value:web3.toWei("1", "ether")  
}, console.log)